1. Field of the Invention: The invention relates to a fluid pressure actuated pack-off for sealing the annulus between a casing and a hanger supported liner after completion of a liner cementing operation.
2. Description of the Prior Art: It is a common practice in subterranean wells, particularly in wells of significant depth, to extend the main casing only a portion of the distance into the well and then provide a liner hanger for supporting a smaller diameter liner extending to the lower portions of the well. It is also desirable that the liner be cemented in the well bore. For this reason, the hangers normally employed to suspend liners within a well bore are not provided with fluid pressure actuated pack-off device would be highly desirable in such applications, but the practical difficulties of isolating the fluid pressure responsive portions of the device from the cementing fluid during the cementing operation and then achieving reliable operation of the fluid pressure actuated pack-off after the cementing operation, have not heretofore been overcome. Moreover, it is highly desirable that the fluid pressure actuated pack-off be carried into the well in the same trip with the liner, the hanger, and other elements commonly employed for effecting the cementing of the liner in the well bore.